Silencer for gaseous streams



June 12, 1956 e. M. WALTON ETAL SILENCER FOR GASEOUS STREAMS Original Filed Feb. 13, 1948 2 Sheets-Sheet 1 3 INVENTORS GEOQGE M ML TO/l/ ATTORNEYS June 12, 1956 G. M. WALTON ETAL SILENCER FOR GASEOUS STREAMS 2 Sheets-Sheet 2 Original Filed Feb. 13, 1948 INVENTORS 650/265 M 14/44 7'0/l/ M Z 0 i 2 WW M ATTORNEYS 2,749,998 Ice Patented June 12, 195

SILENCER FOR GASEOUS STREAMS George M. Walton, Shaker Heights, and Richard E.

Brown, South Euclid, Ohio, assignors to Air-Maze Corporation, Bedford Heights, Ohio, a corporation of Delaware Original application February 13, 1948, Serial No. 8,088, now Patent No. 2,661,072, dated September 22, 1953. Divided and this application January 28, 1953, Serial No. 333,746

2 Claims. (Cl. 181-50) This invention relates to improvements in a silencer for use with a stream of air or other gas flowing to a fan, blower, or supercharger or the like.

This application is a division of our copending application Serial No. 8,088, filed February 13, 1948, for Silencer, now Patent No. 2,661,072, issued September 22, 1953.

One of the objects of the present invention is to provide a silencing device adapted to silence sound waves of the order of two thousand cycles per second and higher.

Another object of the present invention is to provide a novel device for silencing sound waves of the order of eight hundred to two thousand cycles per second.

Still another object of the invention is to provide a novel silencer for a turbocharger wherein the arrangement for silencing is combined in a novel manner with means for providing lubricant to the apparatus producing the sound.

Other objects and advantages of the present invention will be apparent from the accompanying drawings and description and the essential features will be set forth in the appended claims.

In the drawings,

Fig. 1 is a side elevational view of a turbine driven supercharger equipped with our invention;

Fig. 2 is an enlarged sectional view of the same taken along the line 22 of Fig. 3;

Fig. 3 is an enlarged sectional view taken along the line 3-3 of Fig. 1 or a transverse sectional view taken along the line 33 of Fig. 2;

Fig. 4 is a view of a modification showing in part a side elevational view and in part a central sectional view taken along the line 4-4 of Fig. 5;

Fig. 5 is a sectional view taken along the line 55 of Fig. 4.

The device shown in Fig. 1 comprises a gas turbine having an inlet at 11 and an outlet at 12 for exhaust gases from a diesel engine or the like. This turbine drives an air supercharger indicated at 13 and having an air inlet at 14 (Fig. 2) for air admitted through the combination filter and silencer indicated at 15. As shown in Figs. 1, 2, and 3, an outer casing 16 supports two arcuate filter elements 17, each of which is preferably confined between expanded metal plates 18. Air entering in the direction of the arrows of Figs. 2 and 3, after passing through the filter elements, enters an annular throat 19 moving in a radial direction as clearly shown in Fig. 2. The air stream then turns and moves in an axial direction through an annular passageway 20 which communicates with the opening 14 leading to the supercharger 13.

The construction of the silencing portions of the member may be clearly understood from Figs. 2 and 3. A base plate 21 is secured by suitable means not shown to the supercharger 13. Rigid with this base plate is a cylinder 22 which supports the housing 16 already mentioned. The interior wall of the cylindrical plate 22 is covered by soundproofing material 23 which may be of felt, cotton, or other similar material held in place by a cylindrical layer 24 of woven wire screen, hardware cloth, or the like, which in turn is held in position at one end by the ring 25 and at the other end by the binding ring 26. The other wall of the annular passageway 20 is formed by means of a cylindrical plate 27 which is rigidly secured at its outer end to a flared ring 28 which in turn is rigidly mounted on the housing 16. The outer face of the wall 27 is provided with a layer of soundproof material 29 which is similar to the soundproofing material 23. This layer is held in place by a cylindrical layer 30 of woven wire screen, hardware cloth, or the like, which is held at one end by means of a frusto-conical ring 31 rigidly secured to the plate 27. At its other end a binding ring 32 holds the soundproofing material in place. The end plate 16a of the housing 16 is soundproofed opposite the chamber 20. This is accomplished by fixing an annular ring 33 of soundproofing material to the plate 16a by means of a binding ring 34 and a layer 35 of woven wire screen, hardware cloth or the like.

The space located centrally of the cylindrical wall 27 is utilized for the introduction of lubricating apparatus necessary for the lubrication of the rotating parts of the turbine 10 and the supercharger 13. A skirt 36 is secured to the end wall 16a spaced from the end of the opening of the cylinder 27. This skirt 36 is closed on all sides except the bottom where lubricant pipes are adapted to enter. Practically no air will be drawn through the opening 37 at the bottom of the skirt 36 because of a sleeve 38 secured to the inner end of the wall 27 and extending through the center of the rotating parts so as to supply oil thereto. To prevent noise being transmitted through the skirt 36 the inner face thereof is lined with a sound deadening layer 39 held in position by means of a layer 48 of woven mesh screen or the like which in turn is held in place by a U-shaped ring 41 secured to the skirt 36.

In apparatus of the type described, very high pitched sounds are transmitted back along the air stream through the chamber 20 and the annular throat opening 19. These sounds are of the order of two thousand cycles per second and higher. We find that such sounds are reduced to an acceptable audible level if the annular area across the dimension A and circumferentially around member 26 of Fig. 2 is approximately between one hundred and one hundred and fifty per cent of the annular area indicated at B in Fig. 2, which is the annular area included between cylindrical members 24 and 30. If the area at A is perceptibly above one hundred and fifty per cent of the area at B, there is a great loss in the efiiciency of the silencing. Obviously the sound waves impinge freely upon the insulating material 29, 23, and 33 through the screen layers 30, 24, and 35 respectively.

The modification of Figs. 4 and 5 is used for the silencing of sounds of the order of two thousand cycles per second and higher, in such cases as do not require the central opening for the introduction of lubricating pipes as shown in our first described form. Here the base plate 42 is provided with studs 43 for attachment to the supercharger fan or blower. A cylindrical wall 44 is rigidly secured to the base plate 42 and is stiffened by means of the braces 45 if necessary. Spacer members 46 are rigidly secured to the outer end of the cylinder 44, for instance, by means of the welding shown at 47. At the outer ends of these spacer members we secure a plate 48 rigidly attached to the spacer members as by welding through the insulation retainer ring 49. Studs 50 are rigidly secured to the plate 48. A top cover plate 51 is held in position by thumb nuts 52 secured to the studs 50. Held between the plate 51 and the base plate 42 is an annular filter element 53. Air entering through this filter element passes in the direction of the arrows of Fig. 4 first through the annular throat 54 and then through the central opening 55 to the supercharger or the like. The inner face of wall id is lined with soundproofing material 56 of felt, cotton, or the like, held in position by a layer 57 of woven wire screen, hardware cloth, or the like. At its inner end a ring 58 holds the soundproofing material in position and at its outer end a binding ring 59 also holds the soundproof layer to the wall 44. Axially opposite the chamber 55, the plate 43 is provided with a lining of soundproofing material 60 which is held in position by a layer 61 of woven wire screen or hardware cloth which in turn is held by the ring 49 previously mentioned.

As in the first described form, we prefer to make the annular area indicated at C in Fig. 4 between one hundred and one hundred and fifty per cent of the area indicated at D across the chamber 55. If C is substantially greater than one hundred and fifty per cent of D then there is a loss in silencing efficiency. Obviously any sound waves traveling outwardly along the air stream will impinge upon the sound deadening layers 56 or 60 before they can be transmitted into the room.

What we claim is:

1. A silencer for a gaseous stream rushing to an inlet for a turbine or the like and consisting of only two substantially imperforate cylinders of different diameter and coaxial with said inlet enclosing an annular space between them, said annular space communicating with said inlet, linings of sound absorbing material on the outer face of the inner of said cylinders and on the inner face of the outer of said cylinders, a pad of sound absorbing material axially opposite said annular space and spaced from the end of the outer of said cylinders away from said inlet so as to provide a throat inlet for said stream between said pad and the outer of said cylinders, and said throat inlet having an area measured circumferentially between said pad and the adjacent end of said outer cylinder of the order of one hundred to one hundred and fifty per cent of the cross-sectional area of said annular space between said cylinders in a plane normal to the cylinder axis.

2. A silencer, for a stream of air or the like, consisting of a substantially imperforate cylindrical tube, a lining of sound absorbing material covering substantially the entire inner face of said tube and in substantially free communication with said stream, a pad of sound absorbing material concentric with and opposite and spaced from the upstream end of said tube so as to provide there a throat inlet for said stream between said pad and said tube, and said throat inlet comprising the sole inlet for air traversing said tube and having an area measured circumferentiaily between said pad and the upstream end of said tube of the order of one hundred to one hundred and fifty percent of the stream-traversed cross-sectional area of said tube in a plane normal to the tube axis.

References Cited in the file of this patent UNITED STATES PATENTS 1,115,873 Spencer Nov. 3, 1914 2,050,581 Orem Aug. 11, 1936 2,064,207 Jacob Dec. 15, 1936 2,164,365 Wilson July 4, 1939 2,661,072 Lemmerman Dec. 1, 1953 FOREIGN PATENTS 493,538 Great Britain Jan. 5, 1937 

